The present invention relates to a fabric raising or grinding machine including positively controlled fabric raising or grinding cylinders.
Prior raising or grinding machines conventionally comprise a plurality of working cylinders which are circumferentially arranged on a supporting framework, which can turn about a rotary axis therefor.
The working cylinders, in particular, are rotatively driven by a trapezoidal belt, which has the drawback of modifying, as the operating temperature is increased, the friction coefficient, thereby causing the RPM's of the driven pulleys to change.
An analogous problem is due to the wear of the belts, which enter the pulley grooves with an increased depth, thereby changing their original contact diameter and, consequently, causing a variation of the RPM's of the driven pulleys, as well as of the working cylinders.
Moreover, with the trapezoidal belt driving system, since the mentioned trapezoidal belts have a very small contact with the pulleys of the working cylinders, it is not possible to provide raising forces above a given threshold, since the belts tend to inevitably slip with respect to their pulleys, thereby limiting the operating performance of the fabric raising machine and, accordingly, the raising effect thereof on the fabric being raised or ground.
In order to overcome the above mentioned drawbacks, fabric raising or grinding machines have been already constructed, including a positive drive system, comprising a plurality of gear elements which are mutually engaged with one another.
This type of driving system, however, has the drawback that it is very noisy and very complex construction-wise, thereby it has been practically abandoned.